Hitachi Relion 670 Series Applications Manual page 158
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- Applications manual (354 pages) ,
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Section 8
Current protection
~
IEC09000022 V1 EN-US
Figure 58:
~
IEC09000023 V1 EN-US
Figure 59:
The function shall not operate for any of the calculated currents to the protection. The minimum
theoretical current setting (Imin) will be:
Im
in MAX I
EQUATION284 V2 EN-US
A safety margin of 5% for the maximum static inaccuracy and a safety margin of 5% for maximum
possible transient overreach have to be introduced. An additional 20% is suggested due to
inaccuracy of instrument transformers under transient conditions and inaccuracy in the system data.
The minimum primary current setting (Is) is:
I
= 1.3 × I
s
EQUATION285 V3 EN-US
In case of parallel lines with zero sequence mutual coupling a fault on the parallel line, as shown in
Figure 60, should be calculated.
152
I
fB
A
Z
Z
A
L
IED
Through fault current from A to B: I
I
fA
A
Z
Z
A
L
IED
Fault
Through fault current from B to A: I
,
I
f A
fB
min
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B
Z
~
B
Fault
IEC09000022-1-en.vsd
fB
B
Z
~
B
IEC09000023-1-en.vsd
fA
1MRK506375-UEN Rev. N
(Equation 39)
(Equation 40)
Railway application RER670
Application manual
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